Free online MP4 to MTS converter

An AVCHD camcorder, authoring application, or older video editor may require an MPEG transport stream instead of an MP4 file. Converting creates a usable .mts stream, but hardware that expects a complete AVCHD card may also require specific codecs, parameters, and directory metadata.

What the MP4 format is

MP4 is a multimedia container standardized as MPEG-4 Part 14 and based on the ISO Base Media File Format. Phones, action cameras, screen recorders, streaming downloads, and desktop editors such as Adobe Premiere Pro, DaVinci Resolve, and Final Cut Pro commonly use it.

An .mp4 file often contains H.264 or H.265 video with AAC audio, but the extension does not identify the codecs. MP4 can also contain subtitles, chapters, metadata, and multiple audio or video tracks. Its efficient compression and broad software support make it suitable for general playback, sharing, and editing.

What the MTS format is

MTS is a filename extension commonly used for an MPEG-2 Transport Stream containing AVCHD video from consumer camcorders. Typical AVCHD content uses H.264/AVC video with camera-specific profiles, levels, frame rates, and bitrates, plus 48 kHz AC-3 or LPCM audio. The related .m2ts extension is also used for transport-stream video, especially in Blu-ray-related workflows; the extension alone does not define the exact specification.

Transport streams are designed for continuous recording and transmission. MTS is useful when the receiving software or device specifically expects AVCHD-style transport-stream media. It does not improve image quality, and renaming input.mp4 to input.mts does not convert the file.

Convert with 101convert.com

You can convert the file for free on 101convert.com without installing software. Upload the MP4, choose MTS as the output format, start the conversion, and download the result when processing finishes. This is suitable for ordinary playback or software workflows; use local conversion when the footage is confidential, very large, or needs exact AVCHD settings.

Convert with FFmpeg

FFmpeg is a desktop command-line converter for Windows, macOS, and Linux. Install a current build, open a terminal in the folder containing the source file, and replace the example filenames with your own.

If the source already contains codecs accepted by the destination, remux the streams without re-encoding:

ffmpeg -i input.mp4 -map 0:v:0 -map 0:a:0? -c copy -f mpegts output.mts

Remuxing changes the container, so it is fast and preserves the encoded video and audio without another generation of quality loss. It cannot change H.265 to H.264, AAC to AC-3, progressive video to interlaced video, or an unsuitable frame rate to a device-compatible one. A destination that requires Blu-ray-style 192-byte packetization may need FFmpeg's -mpegts_m2ts_mode 1 option, but ordinary AVCHD and MPEG-TS applications do not all require it.

For an MP4 containing H.265, incompatible H.264 settings, unsupported audio, or parameters rejected by the target, transcode the streams:

ffmpeg -i input.mp4 -map 0:v:0 -map 0:a:0? -c:v libx264 -preset medium -crf 18 -profile:v high -pix_fmt yuv420p -c:a ac3 -b:a 256k -ar 48000 -f mpegts output.mts

This produces H.264 video and 48 kHz AC-3 audio, common choices for AVCHD-style workflows. It is not automatically compliant with every camcorder: resolution, frame rate, interlacing, H.264 level, bitrate, GOP structure, and maximum file size may also be restricted. A higher CRF value creates a smaller file with more quality loss; transcoding always takes longer and can introduce generation loss.

Use desktop software

Shutter Encoder provides an FFmpeg-based graphical interface. Add the MP4, choose Rewrap when the existing streams are compatible, select MPEG-TS output if available, and save with an .mts extension. Choose a transcoding function when the source uses H.265, unsupported audio, or video parameters rejected by the destination.

A video editor may offer an Export or Deliver option with an AVCHD or MPEG transport stream preset. Select the required resolution, frame rate, scan type, H.264 profile and level, bitrate, and audio format instead of changing only the filename. Verify the exported file in the actual editor, authoring program, or hardware player.

Quality and compatibility limits

Remuxing preserves the original encoded quality but usually does not reduce file size. Re-encoding can reduce quality and may produce a larger file when the MP4 used efficient H.265 compression. Whenever possible, transcode from the original recording rather than from an already compressed export.

A standalone .mts file is not necessarily a complete AVCHD card. Camcorders may require a structure such as PRIVATE/AVCHD/BDMV/STREAM with matching files in CLIPINF, PLAYLIST, and other directories. A file that plays in VLC can still fail when copied back to a camera or imported into hardware-specific software.

Before converting, check the destination specification for H.264 profile and level, resolution, progressive or interlaced scanning, 50/60 Hz frame rate, maximum bitrate, audio codec, 48 kHz sampling, packetization, file-size limits, and required directory structure. Keep the original MP4 until the converted file has been tested on the intended device or application.